In order to radially secure a tubular internal conductor section in the area of an internal conductor plug-and-socket connection, the respective end of the internal conductor section can be provided with a tubular end piece, which is firmly connected to the rest of the internal conductor section and, for reasons of assembly and to compensate for temperature-related length changes, is also used as a plug-and-socket contact for a socket arranged at the end of the other internal conductor section end piece is form-fittingly surrounded, in the area of a central feed-through bore of a disk-shaped conical post insulator, by the latter, for which purpose the smallest internal diameter of the feed-through bore is selected to be smaller than the outer diameter of the internal conductor section, and the tubular end piece is provided with a profile in this area. The post insulator is also axially secured with its outer edge in the contact area of the two mating external conductor sections, the internal conductor plug-and-socket connection has approximately the same diameter as the internal conductor and is surrounded by a tubular shield electrode (German Patent 26 25 255 A/U.S. Pat. No. 4,053,700). In another internal conductor plug-and-socket connection with a similar function, the tubular end piece is designed as two pieces. Each of the two pieces forms a control electrode that radially extends beyond the internal conductor two pieces are secured with this control electrode against two short annular flanges in the area of the feed-through opening of the respective post insulator and friction-locked together through the feed-through opening. One head-shaped piece is directly connected to the tubular piece of the internal conductor section. The other piece, provided with an attachment flange, changes over into a socket, which has a hollow cylindrical sliding contact, which in turn encloses the end, designed as a cylindrical plug contact, of the adjacent internal conductor section. (European Patent No. 0 660 479 A1).
In another conventional power transmission system (German Patent Document No. 73 23 367) the transition area between two internal conductor sections designed as a plug-and-socket connection has a considerably smaller diameter than the outer diameter of the internal conductor and is surrounded by a shield sleeve that is in displaceable contact with one internal conductor section. The respective ends of the tubular internal conductor are provided with end pieces also referred to as transition pieces, one of which encloses a hollow cylindrical socket, mounted in a ball shape, and the other one is provided with a tubular plug-and-socket contact, on whose cylindrical surface the socket is axially displaceably mounted.
The the internal conductor also can be axially secured in the area of a rigid conductor connection by providing both ends of the internal conductor sections with head-shaped end pieces, which are friction-locked with one another through the feed-through bore of the disk-shaped post insulator and axially and radially positively secured in this feed-through bore. For this purpose, one of the head-shaped end pieces is provided with steps, which, together with the other head-shaped end piece, forms a kind of constriction with which the post insulator engages. In the area of this constriction, the head parts are slightly rounded in order to avoid strong increases in the intensity of the electric field (U.S. Pat. No. 3,372,226, Swiss Patent No. 453 460/U.S. Pat. No. 3,331,911).